1. Field
The following description relates to a technology for recognizing a voice command, and more particularly, to an apparatus and method for recognizing a voice command in an interactive voice user interface.
2. Description of the Related Art
Today's interactive voice interfaces have expanded into many different devices that include systems for booking a plane or a train and systems for withdrawing money like automated teller machines (ATMs). To properly use a system equipped with an interactive voice interface, there must be an appropriate dialogue model set in the system. In general, there are two representative dialogue models for recognizing a voice command, a rule-based dialogue model and a statistical dialogue model. The rule-based dialogue model uses a hypothesis that may be formulated according to a dialogue between a user and an interactive voice system to recognize the intention of the user. However, the rule-based dialogue model is required to enter frequently-used utterances, and all possible answers for the utterances, into an interactive voice system, thus making it difficult to properly handle various voice recognition errors.
The statistical dialogue model makes a probabilistic assumption based on the probabilities of results from voice recognition, and an appropriate response to an input voice command is determined based on those probabilistic assumptions. The statistical dialogue model, unlike the rule-based dialogue model, does not require all the possible utterance responses to be configured. In addition, the statistical dialogue model involves confirming the input voice command upon the occurrence of a voice recognition error and can thus contribute to the establishment of a stable dialogue model.
However, the statistical dialogue model may not be able to operate properly, especially when a user gives multiple commands or requests multiple searches at the same time. Problems may also occur when the intention of the user is not consistent throughout the course of the dialogue between the user and the interactive voice system. For example, a problem may occur when a user continues to issue commands that belong to different domains as compared to those of previous commands because the statistical dialogue model simply accumulates and updates the intentions of previous commands, but may struggle to keep up with changes in the intention of the user.